a. Field of the Invention
The instant invention is directed toward transseptal puncture needles and transseptal puncture needle assemblies. More specifically, it relates to curved transseptal puncture needles and needle assemblies that facilitate insertion through curved transseptal introducers.
b. Background Art
Transseptal puncture needles are used by physicians who perform specialized invasive cardiology techniques. For example, it is known to access the left atrium using a transseptal approach for catheter ablation of arrythmogenic tissue. During such an approach, a physician uses a transseptal introducer and a long, curved needle for left atrial access from the venous system. The introducer, which is curved to facilitate access to a desired portion of the left-heart anatomy, includes a sheath and may include a separate dilator. The curved needle may be, for example, a stainless steel Brockenbrough curved needle or a trocar.
The curved needle is used to make the transseptal puncture after the curved transseptal introducer is used to guide the needle into position. In particular, once the transseptal introducer is in the right atrium, the distal tip of the guiding introducer is positioned against a puncture site, such as the fossa ovalis in the inter-atrial septal wall. The Brockenbrough needle is then advanced distally through the transseptal introducer beyond the distal end of the introducer until it punctures the fossa ovalis. If the introducer includes a dilator, the dilator may be advanced with a needle through the punctured fossa ovalis to prepare an access port through the septum and into the left atrium. Once the sheath has been seated across the septum and in the left atrium, the dilator, if present, and the needle may be withdrawn from the sheath. This sheath then provides lumenal access into the left atrium for direct insertion of, for example, a treatment or diagnostic catheter.
An example of an existing transseptal puncture needle assembly, which comprises the combination of a transseptal puncture needle and stylet, is available from Unimed SA of Lausanne, Switzerland under their part number UMEDST-1 or BRK-1, which is also known by St. Jude Medical, Daig Division, Inc. part number 20601. An example of an existing transseptal introducer is the Swartz SL4 introducer available from St. Jude Medical, Daig Division, Inc.
To facilitate insertion of the curved needle through the curved transseptal introducer, a stylet is inserted into the cannula of the needle. The stylet is a flexible rod that stiffens the curved needle and gives it form during its passage through the curved transseptal introducer.
In order to minimize the risk of inadvertently puncturing the left atrial wall just after crossing the septum, it is important that the transseptal puncture needle is sharp to reduce the amount of insertion force required. If excessive force is required to insert the needle through the introducer or to puncture the inter-atrial septum, the transseptal puncture needle may inadvertently puncture the atrial free wall, the aorta, the inferior vena cava, or the coronary sinus, for example.